Reaction of N 2 O 5 with H 2 O on bulk liquids and on particles and the effect of dissolved HNO 3

Measurements of the reaction probability (γ) of N 2 O 5 on ∼60 wt% H 2 SO 4 were performed at 201 to 230 K on bulk liquids and at 230 K on aerosol particles. The bulk and aerosol results are in good agreement (less than 10% difference). The measurements on bulk liquids show very little change in γ with temperature from 201 to 230 K. HNO 3 was added to the bulk liquids at ∼201 K and to aerosol particles at 230 K (the H 2 SO 4 ‐content was decreased to keep water activity approximately constant). For [HNO 3 ] levels of 1‐to‐15 wt %, the N 2 O 5 reaction probability decreased by ∼15% from that measured on HNO 3 ‐free 60 wt% H 2 SO 4 . For 60 wt% H 2 SO 4 aerosol in the stratosphere ([HNO 3 ] ∼0.3 wt%) the decrease in the N 2 O 5 hydrolysis reaction probability due to HNO 3 would be small.